Resistance welding electrode



July. 10, 1928.

' G. A. LUTZ RESISTANCE WELDING ELECTRODE 2 Sheets-*Shet 1 Filed Oct. 21, 1926 INVENTOR July 10, 1928.

G. A. LUTZ RESISTANCE WELDING ELECTRODE Filed Oct. 21, 1926 2 Sheets-Sheet 2 INVENTOR Qeo /7. L uzz 4. 62 (3 A TTORNEY Patented July l0, l9Z8.

r v w i UNITED STATES 1,676,656 PATENT oFrlcE,

GEORGE'A. LUTZ, or CRANFORD, NEW JERSEY, ASSIGNOR To AMERICAN CIRCULAR Loom: COMPANY, or PITTSBURGH, PENNSYLVANIA; A QORPORATIQII or TENN SYLVANIA.

' nEsIsTAncE WELDING ELECTRODE.

Application filed October 21, 1926. Serial No.143,105.

Heretofore, so fanas I am aware, in the electric Welding-of seams of'relativelythin metal pieces, such as for welding metal tubes, the seams of the tubular stock have 5 been passed between electrodes, whereby a high welding heat is generated in the metal along theseani forwelding the edges of the seam together. In some machines for such purpose a good continuous weld has been the terminal electrodes at a relatively moderate speed, say, from 20 feet to 3O feet per minute more or less, producing what is commonly called a continuous fweld., But an objection has been found in that the metal has formed what is called a bur or projec- 7 tion along the seam, requiring mechanical operation to remove the bur, such as by. grinding the same to make a smooth joint machine carrying out welding as last set forth is set forth in United States Letters Patent to Parpart, No. 658,741, granted September 25, 1900. "In another class of electric welding machine the bur along the seam of the tube or pipe has been practically eliminated by passing the tube stock along the electrodes at a considerably increasedspeed relative to the flow of the electric current such as feet to 70 feet per minute, more or-less. But in such machines a good close weld has not been produced but a weld in the form of closely spaced welding intervals or what is called a recurrent welding effect, or inv which the texture of thew metal which forms the seamds nonuniform. That 'is to say, the welding of the abutting edges of the metal is not actually continuous at all points. Tubing of the character last set forth is disclosed in Letters Patent to Johnston, No. 1,388,434, granted August 23, 1921. WVelded metal tubes or pipesrset forth in said Johnston Letters Patent are used for various purposes, such as where a cheap thin-walled tube is desired, Tubing of the Johnston patent can be made substantially free from bur along a seam because of the speed of feed of the tube stock relatively to the cycles of the welding current and the re- 50 0d set forth in the Johnston patent is not produced where the stock has been fed along 1 or smooth surfaceon the tube or pipe. A Y

current form of the Weld. Where a tube orpipe' having a continuous close weld is de-' sired without a bur along the seam the methalong the seam. Q

The object of my invention is to produce a welded seam in metal tubes, pipes or sheets which shall have a substantially continuous 1 I I I I I tinct welds or recurrent Welding effects weld without the production of a bur along 60 the seam, Wherebyby merely passing the stock between electrodes my improved tube; I may be made without requiring the removal, of a'bur along the-seam. H

In carrying out my invention seam of the stock between terminal electrodes included in an alternating current circuit and at the welding point I oppose the seam witha mechanical resistance sufiicient to prevent the edges of the stock.,that are heated to a Welding temperature from rising or protruding from the stock, whereby as the Welded portion of the seam advances from the electrodes the surface ofthe seam will be substantially smooth and without bur or protuberance; My improved effect can beaccomplis'hed regardless of the speed of travel of the stock with respect to the-electrodes. y

In carryingout my invention I provide'so spaced terminal electrodes to bear on the stock to be Welded adjacent to a seam, be-

tween abutting or opposing edges of the stock for the passageof welding current through the latter, and I locate between the.

electrodes a member adapted to bear against the seam alon the welding edge, and not in circuit with t e electrodes, whereby as the seam is heated during-the passage of the stock along the electrodes said member will keep the'metal at the edges of the stock from ,protrudi-ng and a substantially smooth welded seam will be producedf Y In the example of my invention illustrated in the accompanying drawings I provide, two spacedv annular electrodes adapted to bear on the stock to bewelded on opposite, sides of the seam between the abutting edges of the stock, and between 'said electrodes .1 provide a member having its periphery subloo stantially coincident or in the same radius' with the surfaces of the electrodes that bear on the stock, the member being in position to engage the stock at the point of the welding heat so as to resist protruding or rising of theheated metal beyond the" surface of 1 the stock to prevent the formation ofa bur or ridge along the seam I pass the 65 "ably spaced 'apartJ'The electrodes 1 and 2 are particularly adapted, as illustrated, for

, ing drawings forming a part hereof, Where My invention further comp-risesnovel details of improvement that .Will be more fully hereinafter set forth and then pointed oht in the claims. 4

Reference is to be had to the accompanyinember therebetween, accordingto Fig.,1;.

Fig. 3 is a face view'of part of Fig. 1; Fig. 4 is as. enlarged central section;

Fig. 5 is a side View of the bur-resistingmember;

-fications and Fig. 6 is a face view of contact portions;

Figs. 7 and 8 are sectional details of modi- Fig. 9 is a partly-sectional side view-illustrating a modification.

'. Similar numerals of reference indicate corresponding parts in the several views.

At 1 and 2 a pair of secondary terminal electrodes; are indicated located side by side and spaced apart withinsulation 3 therebetween. In Figs '1 to 8' the electrodes areshown as annular and may lie secured together by insulated screws 4, (Fig. 4), suituse in an electric transformer having ro- '.tative electrodes, such as set forth in my Letters Patent No. 1,594,891, granted August 3, 1926, wherein the conta dt terminal electrodes and the primary and secondaryof the transformer rotate as a unit. At 5 a shaft or axis pcirtion of'the secondary of a rotative transformer is indicated, such as set forth in mysaid Letters Patent, a portion of the transformer shell being indicatedat 6in Fig. 1. The electrode -1 is shown secured to ,the transformer part 5 by" .screw threads at 7 (Fig. 4), and said'elctrode supports the electrode2 out of contact witlf the part 5, as indicated at the opening or space 8. a

Where the electrodes are to be used. for.

welding the seam of stock for tubes or pipe s 9, (Fig.1), the outer surfaces of the elec-- trodes are grooved or recessed at 1, 2, to

substantially conform in radius to the radius of the tube orpipe. At; 10 is indicated a feed compressing roll which,when used for welding tubes or pipes, will have'a grooved periphery at 10 substantially corresponding to the radius of the groove of the electrode,f

stock is the form of flat metal sheets 9" the.

"contact surfaces of the electrodes and 0f the ne'raezsc C roller '10 may be flat, as indicated in' Figs. 7 7 and 8. When the stock to: be welded is between the electrodes and the rollerilO and the electrodes are rotated the stock or blank will be fed at a desired speed and the flow of the electric current between the electrodes will cause Welding heat at the seam of the blank or stock for welding the edges of the metal at the scam in a well known way.

Between the electrodes 1 and 2 I place a member 12 that is adapted to bear against the metal stock being welded at the abutting edges thereof along the seam, at the welding location,coincidentwith the contact of the electrodes against the,stock. "The periphery ripheries of the electro es, and is preferably curved according to the radius of the.electrode recesses 1? and 2 to correspondingly engage the tube stock at the seam thereof. The member12 may bemade of suitable heat at the seam of the stock, and I preferably use a high heat and electrical resisting alloy, such as an alloy of copper and-tungsten. The member 1 2 is insulated from the electrodes 1 and 2' and is-preferably'sec'ured to at least one'ofthe electrodes. In Figs. v1 to 8 the. member 12'is shown located between the insulation 3 so as to be out'of electrical circuit with the electrodes. The member 12 is shown secured to one of the electrodes, (such as the electrode 1), by means of screws 13 that pass through said member and through the interposed insulation 3 and are screwed into a threaded bore in insulating bushings 14; secured in bores 15 in'th'e electrode, whereby the peripheries of the member 12 and of. the electrodes "are re tainediin operative relation and rotate in unison? The heads of the screws 13 are insulated from the electrode 2' by the,interposed: insulation 3. l

In the form shown in Figs. 1 to 8 the electrodes l and 2 arev side by side and parallel, while in Fig. 9 the electrodes are at an angle to one another and suitably spaced apart-,to

ofmember 12 preferably conforms to the pemetal adapted to withstand the welding of the longitudinal seam or joint between the abutting edges phereof. In Fig. 9 the 1 and "insulated therefrom in themanner before described, the periphery of said member bearing M1301} the stock at the seam or joint. The peripheries of the electrodes and of member 12 are curved'to conform substantially to theradius of the tube took. The electrodes 1 and 2v are carried by conducting shafts a and b journaled in bearings 0 and d and supplied with current in a well known .way. 1 p The electrodes may be made in a single piece of suitable conductive metal, such as copper, in a'well'known. way, as illustrated m Fig- ,to ar y a desired current. 'In he member 12 is shown carried by the electrode form shown in Figs. 1 to 7 and 9 I have illustrated operating contactor'surface portions or sections 1 and 2 located'at the peripheries of the body portions 1 and 2 to' 6 engage the metal 9 or 9 to be welded. The

contact portions 1 and 2 may be secured to the. body portions 1 and 2 by means of screws 16, (Figs, 4 and 5), or. by means of silver solder, or by both, or in any desired way. To'enable theworking'contact portions 1"' and 2 of the electrodes td enga e the work or metal 9 without permitting tie bodyportions 1 and 2 to engage said metal I recess the body portions 1 and 29, at their inner edges or corners annularly at 1" and 2 and set the contact portionsor sections 1" and 2 into the respective recesses, where they are secured together in manner before stated. 'The metal of the body portions and of the contact portions of the electrodes t ouch one another at the surfaces of the recesses, as said surfaces are relatively long or extended,

to make good electrical contact for carrying large quantities of current. The contact portions or sections 1" and 2 l e /acne disposed parallel to the axis of the. electrode. The arrangement described "respecting the contact portions .1, 2?, is similar to the corresponding parts set forth in my application for p electrodes, filed August 17, 1926, Serial No. 129,741: v

* The member 112 will preferably be of higher electrical resistance, or electrical and sired or wel of the electrodes are made of a relatively,

" high heat resisting metal compared to the body portionsl and 2,of the electrodes; I preferably use a high heat resisting alloy, such as an alloy 'of copper and tungsten,

fwhich-will withstand the high heat generated at the oints ofcontact of the portions 1 and 2 0 the electrodeswitlf the metal 9- or 9* for welding the latter without the copper of the bod portions l and 2 becoming Injured from t. e heat.

When the edges of rolled sheet metal are to be welded to form tubes or pipes, as in dicated at 9, the outer surfaces ofthe po'r-,

40 tions or sections l and 2 of the electrodes are grooved or recessed at 1 .and 2, (Fig. 4), to substantially conform in radius tothe radius of the tube or pipe. When themetal to be welded is fiat the contact surfaces ofithe portions 1 and 2{ will besimilar, and the contact surfaces or portions 1 and 2 may ef arranged as shown in'Fig.,7, or ins'uch a way that the body portions will not engage the metal 9 to be welded. While-the surfaces of the contact portions or sections. 1 and 2 may be continuous I have shown said portions? in severalsucce'ssive' pieces around thesurfaces of the electrodes, with recemes at 17 between the adjacent ends of said pieces coincidentwith corresponding recesses 18 in the peripheries of the body portions 1 and 2, (Fig. 2). The construction described-provides spaced peripheral contact sections to engage. the metal tobe welded. The recesses 17 and 18 may extend in the material terminal electrode, or said recesses may be heat resistance, than the contact portions 1*, 2 of the electrodes. The seam opposing member 12 is located, at itsperipheral portion, between the adjacent parts of the contact portions 1 and 2*, and insulated there-i from by insulation 3, and their operating peripheries substantially ,correspond for en-" gagerhent with the' stock to be welded. While'the member 12 may be continuous peripherally I have shown the same compris 7 ing several successive pieces which may substantially abut at adjacent ends,to engage the seam of the metal beingwelded. v I

My improvement may be used-in any de- V 1 known form of electric Welding apparatus provided with means-for causing feed of the metal stock'relatively to the electrodes and the seam-resistingmember 12 at a desired speed. When the electric current flows between thepelectrodes through \the metal of the tube or other stock to be welded said metal will be heated to a welding temperature along the seam. The rate of feed of the stock may be such as 'toprod'i1cea good ,close weld, say from 30 to 40 feet per minute. with a suitable alternating "current 100.

flow. The pressure of the electrodes and feed roll or rolls against the tube stock will force the'abutting edges of the metal along I the seam together, providing a path for the current and 'c.aus-ing welding of the es.

nder such conditions and as hereto ore practiced a bur wuld form along the welded 'seam or joint, but in accordance with my invention the seam or joint. opposing mem ber 12 bears, firmly or forcibly 'agalnstv the sure of the rotating electrodes which'would otherwise tend to cause'the heated metal at the seam edges to protrude, into the space.

between the electrodes under the conditions aforestated In other words, simultaneously mm with the flow of the current'along the stock across the seam between the. rotating elec-- trodes the rotating member 12 presses on of the electrodes at anangle to the axes the metal at the seam during travel of the stock to prevent. the formation of abur along the seam.

In the practice of my invention the seams of metal tubes have been weldedwith aclose permanent weld without the formation of a bur or protrusion and with asmooth sur- 139 atent. on electric transformer 70 I ber 12 against the fused r r face alongthe welded portion, and it has not been necessary to grind or otherwise treat the finished welded tube to produce a smooth surfacealong the weld. So-called thin-walled tubing may be produced as well as tubing havingv any gage wall that can be worked in the welding machine. 'l he speed of feed of the stock and the rate of flow of v the electric current relatively thereto niay be in any way desired without raising a bur great advantage in producing electrically butt-welded tubing, since as the tubing \is discharged from the machine it is finished, so far as the welding operation is concerned without. requiring removal-of a bur or the like. I l s Having flow described my invention what lclaim is: I 1. An electrode for welding -metal comprising'a body portion of a highlyconductive metal andla. contact portion of a higher heat resisting metal than the bodj portion secured thereto, and a member adjacent to i the electrode and located in positlonto bear upon'metal being welded to prevent pro trusion of'part of said metal at. the welding point. a

2. Electrodes for welding comprising a pair of annular metallic body portions se-v cured together in spaced relation and having peripheralcontact portions'of higher heat resisting meta-l than the body portions, 40 and an annular member located in the space between said body'portions and insulated therefrom, said member being secured to one of said body portions and having its periphery in (position to bear against the Q edge of stock bein trusion of saidjstoc l I GEORGE 'A. LUTZ.

gkwelded to prevent pro- 

